Monday, November 12, 2012

Early November Smog over Delhi..the How and Why ....See Current Weather Page

An UAC has formed off the Kerala coast, almost at sea level. Some charts even depict it as a low at sea level. Another UAC has formed at 5N and 90E. The 2 UACs joining "line" to form a trough aloft. The Arabian Sea UAC will not sustain beyond 24 hrs, hence the on going medium rains in Kerala and coastal Karnataka decrease after Tuesday.But the Bay system will move NW, initially as a UAC for the next 48 hrs. It will descend as a Low, (BB-11)by the 14th of November, around the 8N and 85E region, East of sri Lanka. The system, BB-11 will move NW towards the TN coast as a depression. Rainfall increasing progressively along TN coast from 15th, and in Chennai from 15th/16th. Centre of the system will be off the TN coast on 16th...As mentioned on 7th, another Low forms around the Andaman region, about 93E. The 2 system can form a strong trough. (Usually called a trough "in sympathy").The tracking of BB-11 and BB-12 will depend on the tilt of the trough. Vagaries reads the situation as BB-11 moving into TN as a depression..The coming WD, currently as a low South of the Caspian Sea region will move into the UAE (Dubai) region on Wednesday 14th. Dubai can expect precipitation on Wednesday. The Low moves into the Iran/Balochistan/Afghanistan region on Thursday, 15th. Here we might see 2 options:a) A strong trough line is seen developing NE from the system into Afghanistan. This may literally pull the WD into the Afghan and adjoining extreme North Pakistan areas.b) The trough mentioned remains weak and not effective. In that case, the WD will be allowed to move E/NE, and move into Northern Pakistan and Northern Indian regions. Precipitation can happen in Kashmir, HP and plains of North Punjab (both sides).

200 hpa jet is from S-SE direction upto 15 degree north latitute but after that it is from SW direction so I think that 98B will move in N-NW direction till 15 degree and after that it will move in the NE direction and will hit the myanmar/Bangladesh coast as depression. What's your views on this Rajesh sir??

TD 25 has formed over western Pacific Ocean near to Bay of Bengal.This tropical depression 25 and strong wind shear over the Bay of Bengal(around 30 knots) will not allow the 98B to intensify beyond low pressure.

@ Rajesh Sir. As per current satellite image some band of clouds are seen entering North Konkan coast. They are spread right from Oman coast till North Maharashtra coast.. So whether they are part of WD system??

shitij: good question. The pressure is high, between 1014 and 1020 in those regions in winter months. But,what is a WD ? It is actually a "cold front" moving in. A cold front is a mass of relatively cold air , pushing beneath a relatively warm air mass, and making the warm air rise. Now when this air mass rises, 2 things happen 1. The pressure in that region falls. Falls from the current 1015 (avg) to 1010. Then 1010 becomes a low in that region. and 2. the rising air condenses to form clouds.The incoming air in the region is hence cold at the surface..check the current MSLP here;see the Low as a WDhttp://www.pmdnmcc.net/WxCharts/SaChart-12-3.JPG